1. Field of the Invention
The present invention relates to optical telecommunication systems and, more specifically, is related with monitoring performance of such systems.
2. Brief Description of Related Developments
In optical telecommunication systems, bit error ratio (BER) and uptime are important measures of the quality of the system. For example, some system elements are required to have uptimes of 99.995% or 99.999%, including both planned and unplanned downtime.
An important way of ensuring high uptime values is to continually monitor the performance of the system elements to locate faults, allowing them to be put right quickly, and to identify defects before they become faults allowing them to be corrected without any unplanned downtime.
A way of monitoring the performance of system elements is by loop-back testing. Such a testing technique provides for a signal destined for a remote location to be instead directed to a nearby receiver; in the case of a transceiver, the signal launched from its transmitter may be returned to its receiver. Often the signal is attenuated to simulate the losses in the optical telecommunication system.
Generally, loop-back testing requires a technician to physically remove the connectors of the optical telecommunication system and replace them with a so-called patchcord, or the connectors of a variable optical attenuator (VOA). The system can then be tested in the loop-back condition and finally the patchcord, or the connectors of the VOA, can be removed and the system connectors replaced.
FIG. 1 shows a transceiver module including transmitter and receiver sub-modules T and R, as well as the associated control electronics E integrated into a housing H to transmit digital input signals I and receive digital output signals O via an optical communication system connected to the housing H via a transmitter connector C1 and a receiver connector C2.
This arrangement is thoroughly conventional in the art and does not require to be described in detail herein.
FIG. 1 shows a typical loop-back testing condition for the system in question where the optical telecommunication system has been disconnected and replaced by a patchcord arranged to receive light from the transmitter T via the connector C1 and re-direct it to the receiver R via the connector C2.
The patchcord typically includes a length of an optical fibre F (currently designated loop-back fibre), possibly including a variable optical attenuator or VOA that attenuates the light. Resorting to such an arrangement requires a technician to physically remove the connectors of the optical telecommunication system and replace them with the patchcord. The system can then be tested in the loop-back condition and finally the patchcord can be removed and the system connectors replaced.
This is a laborious and time-consuming process.
The need is therefore felt for solutions overcoming the disadvantages of the prior art considered in the foregoing.